Transport Properties of Double Quantum Dots Formed by Ferrocene Units

Combining nonequilibrium Green?s function technique with density functional theory, the transport properties of a series of double quantum dots formed by ferrocene dimers with saturated carbon bridges and saturated silicon bridges, [Fc?(CH2)n]2 and [Fc?(SiH2)n]2 (n = 1,2,3), were comparatively studied. We have found that the type and the length of the bridge group between two adjacent ferrocene units plays an important role in governing the transport property. The negative differential resistance is enhanced with the lengthening of the space linker, i.e., the NDR magnitude follows the sequence of [Fc?(CH2)3]2 > [Fc?(CH2)2]2 > [Fc?CH2]2 and [Fc?(SiH2)3]2 > [Fc?(SiH2)2]2 > [Fc?SiH2]2. For the short bridged systems (n = 1,2), the conductivity of molecules with the carbon linkage is higher than that with the silicon linkage, that is, [Fc?CH2]2 > [Fc?SiH2]2 and [Fc?(CH2)2]2 > [Fc?(SiH2)2]2. In addition, [Fc?SiH2] presents a rectifier effect. The effect of the bridge on the transport property could be interpreted from the bonding, the molecular level state, the transmission spectrum, and the density of states. Combining nonequilibrium Green?s function technique with density functional theory, the transport properties of a series of double quantum dots formed by ferrocene dimers with saturated carbon bridges and saturated silicon bridges, [Fc?(CH2)n]2 and [Fc?(SiH2)n]2 (n = 1,2,3), were comparatively studied. We have found that the type and the length of the bridge group between two adjacent ferrocene units plays an important role in governing the transport property. The negative differential resistance is enhanced with the lengthening of the space linker, i.e., the NDR magnitude follows the sequence of [Fc?(CH2)3]2 > [Fc?(CH2)2]2 > [Fc?CH2]2 and [Fc?(SiH2)3]2 > [Fc?(SiH2)2]2 > [Fc?SiH2]2. For the short bridged systems (n = 1,2), the conductivity of molecules with the carbon linkage is higher than that with the silicon linkage, that is, [Fc?CH2]2 > [Fc?SiH2]2 and [Fc?(CH2)2]2 > [Fc?(SiH2)2]2. In addition, [Fc?SiH2] presents a rectifier effect. The effect of the bridge on the transport property could be interpreted from the bonding, the molecular level state, the transmission spectrum, and the density of states.